Advanced solid propellant for antitank propulsion subsystems

ABSTRACT

A NOVEL PROPELLANT COMPOSITION FOR ROCKET MOTORS IN WHICH THE PROPELLANT COMPOSITION COMPRISES A BINER SUCH AS ACRYLATE-ACRYLIC ACID OR FUNCTIONALLY TERMINATED POLYBUTADIENES, NITROGLYCERINE, HMX(CYCLOTETRAMETHYLENETETRANITROAMINE), AMMONIUM PERCHLORATE, CARBON BLACK, AND A CROSSLINKING AGENT.

3,764,418 ADVANCED SOLID PROPELLANT FOR ANTITANK PROPULSION SUBSYSTEMS David C. Sayles, Huntsville, Ala., assignor to the United States of America as represented by the Secretary of the Army No Drawing. Filed Mar. 23, 1972, Ser. No. 238,704

' 7 Int. Cl. C0611 5/06 7 7 US. Cl. 149-1931 3 Claims ABSTRACT OF THE DISCLOSURE A novel propellant composition for rocket motors in which the propellant composition comprises a binder such as acrylate-acrylic acid or functionally terminated polybutadienes, nitroglycerine, 'HMX(cyclotetramethylenetetranitroamine), ammonium perchlorate, carbon black, and a crosslinking agent.

BACKGROUND OF THE INVENTION Double-base propellants have traditionally been used in the propulsion subsystems of antitank weapons. Nitrocellulose-based propellants are particularly attractive for use in propellants for these light assault weapons because of their near-smokelessness, mesaor plateau-burning characteristics over certain combustion pressure regimes, and low temperature coefficients. However there is a need for other propellant compositions that deliver greater specific impulse at substantially the same burning rate and temperature coeflicient.

Accordingly it is an object of this invention to provide a novel propellant composition for small antitank weapons.

Another object of this invention is to provide a propellant composition that uses an ethyl acrylate-acrylic acid binder with nitroglycen'ne, cyclotetramethylenetranitroamine, ammonium perchlorate and a crosslinking agent.

SUMMARY OF THE INVENTION In accordance with this invention, it has been discovered that functionally terminated polybutadienes or copolymers of various acrylates and acrylic acid can be used in propellant compositions with nitroglycerine, HMX (cyclotetramethylenetetranitroamine), ammonium perchlorate, carbon black and a crosslinking agent to produce a propellant for an antitank weapon that delivers an acceptable specific impulse, burning rate and temperature coefiicient.

DESCRIPTION OF THE PREFERRED EMBODIMENT The propellant composition of this invention concerns a propellant based on the following propellant formulation and modifications thereof:

Wt. percent Ethyl acrylate-acrylic acid (95-5) coprepolymer (binder) 4.8 Nitroglycerine 24.5 HMX (monopropellant) 50.5 Ammonium perchlorate (oxidizer) 20.2

Carbon black (opacifier/combustion instability suppressant) 0.5 UNOX 221 (crosslinking agent) 1.05

The above improved propellant is compared with M-7, a double-base composition which is now used in rocket atent ice motors. The M7 propellant has the following composition:

A comparison of the pertinent characteristics of the improved propellant with M-7 propellant is as follows:

Propellant Improved Characteristic propellant M-7 Delivered specific impulse (lb.f.-sec./lb.m.) .234 219 Burning rate (at 1,000 p.s.i.a.) i.p.s 0.7 0.7 Temperature coefficient (pereentF F 0. 24 0. 25

Transmissibility (percent) From the above table in the comparison of the characteristics of the improved propellant with the prior art M7 propellant, it is apparent that the improved propellant offers higher performance with comparable temperature coefficient.

Even though a specific improved propellant composition has been illustrated above, the improved propellant composition may be varied as to the specific ingredients and the amounts thereof as set forth hereinbelow. The binder is preferably ethyl acrylate-acrylic acid in a ratio of 95/5 but may be other acrylate-acrylic acid binders. Other acrylates that may be used with the acrylic acid are methyl acrylate, 2-ethylhexyl acrylate, petrin acrylate, butyl acrylate, ethyl acrylate, etc. The preferred ratio of acrylate to acrylic acid is 95/5, but the ratio of selected acrylate to acrylic acid in the prepolyrner may vary from about /10 to about 06/4. The binder may also be functionally-terminated polybutadienes such as hydroXy-terminated polybutadiene, carboxy-terminated polybutadiene, and etc. The weight percent of the binder should range from about 4 to about 10 weight percent of the propellant composition.

The nitroglycerine present in the propellant composition may range from about 15 to about 30 weight percent. The ammonium perchlorate oxidizer may vary from about 15 to about 25 weight percent. The additive carbon black may vary from about 0.25 to about 2.0 weight percent and a crosslinking agent of about 0.75 to about 1.5 weight percent should be used.

The conventional crosslinking agent, UNOX 221 (4,5- epoxycyclohexylmethyl, 4,5- epoxycyclohexylcarboxylate or diepoxy dicyclohexyl carboxylate) and other conventional curing agents such as bisphenyl A, Epon 828, triglycidylamenophenol, etc., may be used to crosslink the binder materials. Other additives in trace amounts as desired for the particular propellant may be used such as stabilizers ballastic modifiers, processing aids, and the like.

The propellant is formulated using conventional methods and procedures in preparing propellant compositions.

I claim:

1. A propellant composition comprising: a binder selected from the group consisting of acrylate-acrylic acid and functionally-terminated polybutadienes; nitroglycerine; cyclotetramethylenetetranitroamine; ammonium perchlorate; carbon black; and a crosslinking agent, said binder being present in an amount of about 4 to about weight percent, said nitroglycerine being present in an amount of about to about weight percent, said cyclotetramethylenetetranitroamine being present in an amount of about 25 to about Weight percent, said ammonium perchlorate being present in an amount of about 15 to about 25 Weight percent, said carbon black being present in an amount of about 0.25 to about 2.0 Weight percent, and said crosslinking agent being present in an amount of about 0.75 to about 1.5 Weight percent.

2. The propellant composition of claim 1, wherein said binder is ethyl acrylate-acrylic acid in a ratio of about /5, and said crosslinking agent is diepoxy dicyclohexyl carboxylate.

3. The propellant composition of claim 2, wherein said binder is present in an amount of about 4.8 weight percent, said nitroglycerine is present in an amount of about 4 24.5 Weight percent, said cyclotetramethylenetetraanitroamine is present in an amount of about 50.5 weight percent, said ammonium perchlorate is present in an amount of about 20.2 weight percent, said carbon black is present in an amount of about 0.5 weight percent, and said crosslinking agent comprises about 1.05 Weight percent.

References Cited UNITED STATES PATENTS 3,362,850 1/1968 Sutton et a1. 149-92 BENJAMIN R. 'PADGETT, Primary Examiner U.S. Cl. X.R. 

